Filtering with relative dates not accurate, possible TZ bug

We are filtering a graph with a relative “is after or equal to start of month” date. We have 6 items that should be in the graph, three items have the date June 1st, the other three are after the 2nd. With the start of month filter it is not pulling in the items that have date of June 1st. Suspecting this is some sort of timezone or comparison bug?